sedimentary
River Gravel
Polymictic Gravel / Detrital Rock Aggregate
Hardness varies (Mohs 6-7 generally for quartz-rich components), colors range from brown, tan, to gray, vitreous to dull luster, rounded to sub-rounded shape due to aqueous abrasion, variable crystal structure depending on constituent minerals.
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Physical properties
Hardness varies (Mohs 6-7 generally for quartz-rich components), colors range from brown, tan, to gray, vitreous to dull luster, rounded to sub-rounded shape due to aqueous abrasion, variable crystal structure depending on constituent minerals.
Formation & geological history
Formed through the mechanical weathering, erosion, and long-distance transport of various parent rocks by river currents, smoothing out sharp edges over thousands to millions of years in alluvial environments.
Uses & applications
Widely used in construction for concrete aggregate, road base, landscaping, drainage systems, and garden pathways.
Geological facts
River gravel beds are dynamic ecosystems and often preserve various durable mineral fragments like quartz, jasper, and quartzite that survived rigorous transport.
Field identification & locations
Found extensively in riverbeds, floodplains, and glacial outwash plains worldwide; easily identifiable by smooth, rounded surfaces resulting from water tumbling.
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